Process for the production of di- and polyhydroxycarboxylic acids

ABSTRACT

The invention provides an improved process for the manufacture of higher-molecular weight di- and/or polyhydroxycarboxylic acids by the hydrolysis of epoxidized mono- or polyunsaturated carboxylic acids utilizing aqueous solutions of salts of aliphatic carboxylic acids as catalysts at temperatures of over 100*C.

United States Patent 1 Stein et al.

1 PROCESS FOR THE PRODUCTlON OF Dl- AND POLYHYDROXYCARBOXYLIC ACIDS [75] inventors: Werner Stein, Erkrath-Unterbach;

Rainer Osberghaus, Dusseldorf-Urdenbach, both of Germany [73] Assignee: l-lenkel & Cie Gmbl-l,

Dusseldorf-Holthausen, Germany 22 Filed: Nov. 7, 1973 2] Appl. No.: 413,653

[30] Foreign Application Priority Data Nov. 20, 1972 Germany 2256908 [52] US. Cl 260/413; 260/535 R [51] Int. Cl C0811 17/36 [58] Field of Search 260/413, 535 R July 29, 1975 Primary ExaminerLewis Gotts Assistant Examiner-Ethel G. Love Attorney, Agent, or Firm-Hammond & Littell [5 7 ABSTRACT The invention provides an improved process for the manufacture of higher-molecular weight diand/or polyhydroxycarboxylic acids by the hydrolysis of cpoxidized monoor polyunsaturated carboxylic acids utilizing aqueous solutions of salts of aliphatic carboxylic acids as catalysts at temperatures of over 100C.

12 Claims, No Drawings PROCESS FOR THE PRODUCTION OF DI- AND POLYHYDROXYCARBOXYLIC ACIDS THE PRIOR ART The hydrolysis of epoxy carboxylic acids by alkalis or acids is known. However, the manufacture of dihydroxycarboxylic acids and polyhydroxycarboxylic acids in this manner has the disadvantages that the reaction proceeds rather slowly, that undesirable side reactions occur, mainly in the form of homopolymerizations of the epoxide which reduce the yield, and finally that additional operational steps have to be taken for the manufacture of the dihydroxycarboxylic acids and polyhydroxycarboxylic acids by alkaline or acidic hydrolysis. Thus, for example, the acidic hydrolysis results in partial or complete esters of hydroxycarboxylic acids which have first of all to be saponified by alkalis. Subsequently, these saponification products as well as the salts of the hydrocarboxylic acids formed during alkaline hydrolysis have to be converted to free acids, which requires special measures because of the possibility that the hydroxyl groups might esterify.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a process for the production of higher diand polyhydroxycarboxylic acids by hydrolysis of the corresponding epoxides, characterized by carrying out the hydrolysis of the epoxides with aqueous solutions of salts of aliphatic monoand/or polycarboxylic acids using temperatures above lC.

This and other objects of the present invention will become apparent from the following description thereof.

DESCRIPTION OF THE INVENTION The invention concerns a process for the manufacture of higher-molecular weight diand/or polyhydroxycarboxylic acids by the hydrolysis of epoxidized monoor poly-unsaturated carboxylic acids.

Concerning the manufacture of higher diand polyhydroxycarboxylic acids from the corresponding epoxides, it has now been discovered that the abovedescribed drawbacks of the prior art can be obviated by utilizing a process which is characterized by carrying out the hydrolysis of the epoxides with aqueous solutions of salts of aliphatic monoand/or polycarboxylic acids using temperatures above 100C. The preferred temperature range is 200 to 350C.

More particularly, the present invention provides a development in the process for the preparation of higher dihydroxycarboxylic acids and/or polyhydroxycarboxylic acids which comprise hydrolyzing the corresponding epoxycarboxylic acids of the formula R R COOH alkylene having 1 to 21 carbon atoms and epoxyalkylene having 3 to 21 carbon atoms, with the proviso that the epoxycarboxylic acids have a total of 6 to 24 carbon atoms, with a solution of a catalyst, and recovering said acids; the improvement which comprises carrying out said hydrolysis with a catalyst comprising an aqueous solution of salts of an aliphatic carboxylic acid having 1 to 24 carbon atoms selected from the group consisting of a monocarboxylic acid having 1 to 10 carbon atoms, a polycarboxylic acid having 3 to 24 carbon atoms, and mixtures of a monocarboxylic acid having 1 to 24 carbon atoms with a polycarboxylic acid having 3 to 24 carbon atoms, at a temperature above C, said carboxylic acid salts being stable under the reaction conditions and being soluble in the form of their salts.

Suitable salts for carrying out the process of the invention are the salts of carboxylic acids which are stable under the reaction conditions and are soluble in the form of their salts. The respective carboxylic acids can be saturated or unsaturated, monocarboxyl or polycarboxyl, linear or branched compounds or, if so desired, hetero-substituted compounds which can be used individually as a mixture. When monocarboxylic acid salts are used exclusively, then consideration as to sufficient solubility restricts the main choice to compounds having up to 10 carbon atoms.

Examples of suitable salts of carboxylic acids are the monosalts and polysalts of alkali metals such as the lithium salt, dilithium salt, sodium salt, disodium salt, potassium salt and dipotassium salt, and the monosalts and polysalts of alkaline earth metals such as the calcium salt, dicalcium salt, barium salt and dibarium salt.

Examples of suitable carboxylic acids whose abovenamed salts can be utilized according to the present invention when soluble in the reaction mixture, include linear or branched aliphatic monocarboxylic acids having 1 to 24 carbon atoms, preferably 1 to 10 carbon atoms, for example alkanoic acids having 1 to 24 carbon atoms, preferably 1 to 10 carbon atoms, such as acetic acid, propionic acid, butyric acid, capronic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and arachic acid, and for example alkenoic acids having 3 to 24 carbon atoms preferably alkenoic acids having 3 to 10 carbon atoms such as acrylic acid, methacrylic acid and allylacetic acid, lauroleic acid, myristoleic acid, palmitoleic acid, oleic acid, gadoleic acid and erucic acid. Other suitable examples include linear or branched aliphatic polycarboxylic acids having 3 to 24 carbon atoms, preferably 3 to 10 carbon atoms, for example alkanedioic acids having 3 to 24 carbon atoms, preferably 3 to 10 carbon atoms, such as malonic acid, succinic acid, adipic acid, azelaic acid and sebacic acid, and for example alkenedioic acids having 4 to 24 carbon atoms, preferably 4 to 10 carbon atoms, such as maleic acid and fumaric acid.

The salts of dicarboxylic acids having 3 to 24 carbon atoms are preferred and can be used either by themselves or mixed with monocarboxylic acids. In such mixtures, salts of monocarboxylic acids having more than 10 carbon atoms, for example up to 24 carbon atoms, can likewise be present, especially the salts of the dihydroxycarboxylic acid and the polyhydroxycarboxylic acid hydrolysis products to be manufactured according to the process of the invention. These hydrolysis products produced by the process of the invention are monocarboxylic acids having 6 to 24 carbon atoms. as well as having dihydroxy or polyhydroxy substituents.

Generally speaking, preferred examples of salts of aliphatic carboxylic acids having 1 to 24 carbon atoms to be used according to the process of the present invention are the alkali metal salts of carboxylic acids selected from the group consisting of alkanoic acids hav ing 1 to carbon atoms, alkanedioic acids having 3 to 24 carbon atoms, alkenedioic acids having 4 to 24 carbon atoms, a mixture of an alkanoic acid having 1 to 24 carbon atoms with at least one carboxylic acid selected from the group consisting of alkanedioic acids having 3 to 24 carbon atoms and alkenedioic acids having 4 to 24 carbon atoms, and a mixture of a polyhydroxycarboxylic acid hydrolysis product with at least one carboxylic acid selected from the group consisting of alkanedioic acids having 3 to 24 carbon atoms and alkenedioic acids having 4 to 24 carbon atoms.

The proportion of the epoxy acid to the hydrolyzing salt is variable within wide limits, depending upon the temperature. At about 90C, the concentration of the salt solutions should be at least 2 percent, preferably percent to almost saturation. In the case where the starting material contains components which react with and consume the alkali, this loss may be compensated for, by using additional amounts of alkali metal hydroxides or alkali metal salts.

The opening of the epoxy ring by hydrolysis is probably effected by the hydroxy ions which arise upon the hydrolytic splitting of the carboxylic acid salts in aqueous solution. It is to be regarded as completely surprising that there is no reaction of the oxirane ring with the anions of the carboxylic acid salts nor is there any homopolymerization of the epoxide taking place.

During the reaction, cations are not exchanged between the dior polyhydroxycarboxylic acid formed and the salt of the hydrolyzing carboxylic acid. It is surprising that after cooling of the reaction mixture, the dior polyhydroxy acids are almost quantitatively present as free acids and can be mechanically separated from the aqueous solution as a precipitate. The aqueous solution of the hydrolyzing salts can be recycled for further use in the process.

Monoand polyepoxycarboxylic acids having the following formula are to be utilized according to the process of the invention procedures from naturally occurring unsaturated fatty' acids having 6 to 24 carbon atoms or their mixtures. A known epoxidation procedure comprises oxidation by means of peroxyalkanoic acids, such as peroxyformic acid and peroxyacetic acid. under oxidation conditions. Suitable examples of naturally occurring unsaturated fatty acid starting materials having from 6 to 24 carbon atoms include alkenoic acids having 6 to 24 carbon 5 atoms such as lauroleic acid. myristoleic acid. palmitoleic acid. oleic acid. gadoleic acid and erucic acid. hydroxyalkenoic acids having 6 to 24 carbon atoms such as ricinoleic acid, alkadieneoic acids having 6 to 24 carbon atoms such as linoleic acid. alkatrieneoic acids having 12 to 24 carbon atoms such as linolenic acid and clupanodonic acid, and alkatetraeneoic acids having 12 to 24 carbon atoms such as arachidonic acid.

The process of the invention has the advantage that epoxidized carboxylic acids are hydrolyzed to hydroxycarboxylic acids within a short reaction time and without practically any loss of auxiliary chemicals. The yields obtained are quite high and generally are greater than 90 percent of the theoretical yield. A special advantage of the process is that the carboxylic acids to be prepared are obtained as free acids.

The diand polyhydroxycarboxylic acids produced according to the process of the present invention are useful as intermediates in organic synthesis reactions for the preparation of anionic surfactants of the hydroxycarboxylic acid variety by known soap formation techniques, as described in Surface Active Agents. Chapter 2, (1949), Schwartz. et al.

The following examples are merely illustrative of the present invention without being deemed limitative in any manner thereof.

EXAMPLE 1 In a nickel autoclave, 125 gm of 9,10-epoxystearic acid and 500 gm of an aqueous solution containing 19.6 percent disodium azelate were heated to 260C while being stirred. After the reaction temperature had been reached, the reaction mixture was cooled. The resulting dihydroxystearic acid was separated at 90C. The epoxycarboxylic acid was 100 percent converted; and the yield of dihydroxystearic acid was 95 percent of the theoretical.

EXAMPLE 2 In an autoclave equipped with a stirrer, 250 gm of 9,10-epoxystearic acid and an aqueous solution of 207 gm of disodium sebacate in 1,200 ml water were heated to 250C. After cooling the reaction mixture to room temperature, the resulting dihydroxystearic acid was filtered off and dried. The conversion yield of the epoxystearic acid starting material was 100 percent. and the yield of dihydroxystearic acid amounted to 91 percent of the theoretical.

1n an autoclave equipped with stirrer, 1 kg of crude (70 percent) 9,10-epoxystearic acid and an aqueous solution of 0.780 kg of disodium azelate and 0.027 kg sodium hydroxide in 4.8 kg water were heated to 270C. After the reaction temperature had been reached. the reaction mixture was cooled. After the temperature had been lowered to 90C, the crude dihydroxystearic acid formed was separated from the aqueous solution of disodium azelate. The conversion was quantitative. and the yield amounted to 96 percent of the theoretical.

EXAMPLE 4 A procedure analogous to that of Example 3 was utilized, except that disodium azelate was replaced with 0.638 kg disodium adipate. The conversion was quantitative, and the yield of dihydroxystearic acid amounted to 94 percent of the theoretical.

EXAMPLE 5 125 gm crude (70 percent) 9,10-epoxystearic acid together with an aqueous solution of 48.6 gm of maleic acid in 500 gm of an aqueous solution of 7.4 percent sodium hydroxide were heated to 260C. After cooling, the resulting dihydroxystearic acid was separated. The conversion of the epoxycarboxylic acid was 97 percent, and the yield amounted to 77 percentof the theoretical.

EXAMPLE 6 In an autoclave equipped with a stirrer, 125 gm of 9,10-epoxystearic acid and an aqueous solution of disodium azelate which had been prepared from 29.2 gm of azelaic acid and 166 ml of an aqueous solution of 7.5 percent sodium hydroxide were heated to 250C. After cooling to room temperature, the resulting dihydroxystearic acid was filtered off, washed with water and dried. The conversion of the epoxycarboxylic acid was 100 percent: and the yield amounted to 84 percent of the theoretical.

EXAMPLE 7 50 gm of 9.10-epoxystearic acid and an aqueous solution of sodium azelate which had been prepared from 63.2 gm of azelaic acid and 393 gm of an aqueous solution of 7.5 percent sodium hydroxide were heated to 290C. After cooling to 90C. the resulting dihydroxystearic acid was separated. The conversion of the epoxycarboxylic acid was 100 percent, and the yield was 94 percent of the theoretical.

EXAMPLE 8 In an autoclave. 125 gm of 9.10-epoxystearic acid and an aqueous solution of 7 percent sodium acetate were heated to 250C. After cooling to room temperature, the dihydroxystearic acid was filtered off. The conversion of the epoxycarboxylic acid was 96 percent; and the yield amounted to 75 percent of the theoretical.

EXAMPLE 9 in a test series the re-use of an aqueous solution of disodium azelate utilized for the hydrolysis of epoxystearic acid was investigated. 125 grams of crude 70 percent) epoxystearic acid was heated to 250C with an aqueous solution of 97.5 grams of disodium azelate and 3.4 grams of excess sodium hydroxide in 500 ml of water. The dihydroxystearic acid was separated at 90C, and the disodium azelate solution was used over again after addition of 3.4 grams of sodium hydroxide. After reusing the disodium solution 5 times for the hydrolysis each time of 125 grams of epoxystearic acid, the average yield of dihydroxystearic acid was 94 percent of theory.

EXAMPLE 10 125 gm crude (70 percent) epoxystearic acid together with 97.5 gm of disodium azelate, 500 ml of wa- I ter. 28 gm of sodium dihydroxystearate were heated to 250C. After cooling to room temperature, the solid dihydroxystearic acid was filtered off and dried as Prodnet 1. The filtrate was acidified, and the precipitated acid mixture was likewise filtered off and dried as Product II. For determination of the yield of dihydroxystearic acid. the Products I and 11 were titrated with periodic acid. After subtraction of the dihydroxystearic acid which had been used for hydrolysis in the form of sodium dihydroxystearate, the yield amounted to percent of the theoretical. The conversion was quantitative.

EXAMPLE 1 1 A'mixture of epoxy fatty acids was prepared by oxidation with peroxyacetic acid of a fatty acid mixture having the following composition: 21 percent linoleic acid, 52 percent oleic acid, 8 percent linolenic acid. and 19 percent of a mixture of saturated fatty acids having 16 to 18 carbon atoms. gm of the epoxy fatty acid mixture defined above and 500 gm of an aqueous solution containing 20 percent disodium azelate were introduced into a nickel autoclave and heated to 260Cwhile being stirred. After the reaction temperature had been reached, the autoclave was cooled. The resulting" product mixture was separated at 90C. The conversion wasquantitative. The yield of dihydroxycarboxylic acid and polyhydroxycarboxylic acid mixture amounted to 72 percent of the theoretical.

Although the present invention has been disclosed in connection with a few preferred embodiments thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the new invention. All of these variations and modifications are considered to be within the true spirit and scope of the present invention as disclosed in the foregoing description and defined by the appended claims.

We claim:

1. 1n the process for the preparation of higher dihydroxycarboxylic acids and/or polyhydroxycarboxylic acids comprising hydrolyzing the corresponding epoxycarboxylic acids of the formula R C R COOH wherein R R and R are each selected from the group consisting of hydrogen, alkyl having 1 to 20 carbon atoms and epoxyalkyl having 3 to 20 carbon atoms, and wherein R is selected from the group consisting of alkylene having 1 to 21 carbon atoms and epoxyalkylene having 3 to 21 carbon atoms, with the proviso that the epoxycarboxylic acids have a total of 6 to 24 carbon atoms, with a solution of a catalyst, and recovering said acids; the improvement which comprises carry-out said hydrolysis with a catalyst consisting essentially of an aqueous solution of salts selected from the group consisting of alkali metal salts, alkaline earth salts and the mixtures thereof, an aliphatic carboxylic acid having 1 to 24 carbon atoms selected from the group consisting of alkanoic acids having 1 to 10 carbon atoms, alkanedioic acids having 3 to 24 carbon atoms, alkenedioic acids having 4 to 24 carbon atoms, a mixture of an alkanoic acid having 1 to 24 carbon atoms with at least one carboxylic acid selected from the group consisting of alkanedioic acids having 3 to 24 carbon atoms and alkenedioic acids having 4 to 24 carbon atoms, and a mixture of a polyhydroxycarboxylic acid consisting of dihydroxymonocarboxylic acidshaving 6.

to 24 carbon atoms produced by said hydrolysis and polyhydroxymonocarboxylic acids having 6 to 24 carbon atoms produced by said hydrolysis, at tempera ture above 100C, said carboxylic acidsaltfifiing stable under thereaction conditions and being soluble in the form of their salts.

2. The process of claim 1, in which said salts of aliphatic carboxylic acids having I to 24 carbon atoms are salts of carboxylic acids selected from the group consisting of acetic acid, propionic acid, butyric acid, capronic acid, caprylic acid, pelargonic acid, malonic acid, succinic acid, adipic acid, maleic acid, fumaric acid, azelaic acid, and sebacic acid.

3. The process of claim 1, in which said temperature is between 200 and 350C.

4. The process of claim 1, in which said salts of aliphatic carboxylic acids are salts of a dicarboxylic acid having from 3 to 24 carbon atoms.

5. The process of claim 1 in which said salts of aliphatic carboxylic acid consists essentially of a salt of a dicarboxylic acid having 3 to 24 carbon atoms mixed with salts of said polyhydroxycarboxylic acids hydrolysis product.

6. The process of claim 1, in which said salts to be used for the hydrolysis are the sodium salts.

7. The process of claim 1, in which the concentration of the salt solutions is at least 2 percent.

higher fatty acid is epoxystearic acid. 

1. IN THE PROCESS FOR THE PEPARATION OF HIGHER DIHYDROXYCARBOXYLIC ACIDS AND/OR POLYHYDROXYCARBOXYLIC ACIDS COMPRISING HYDROLYZING THE CORRESPONDING EPOZYCARBOXYLIC ACIDS OF HE FORMULA FORMULA
 2. The process of claim 1, in which said salts of aliphatic carboxylic acids having 1 to 24 carbon atoms are salts of carboxylic acids selected from the group consisting of acetic acid, propionic acid, butyric acid, capronic acid, caprylic acid, pelargonic acid, malonic acid, succinic acid, adipic acid, maleic acid, fumaric acid, azelaic acid, and sebacic acid.
 3. The process of claim 1, in which said temperature is between 200* and 350*C.
 4. The process of claim 1, in which said salts of aliphatic carboxylic acids are salts of a dicarboxylic acid having from 3 to 24 carbon atoms.
 5. The process of claim 1 in which said salts of aliphatic carboxylic acid consists essentially of a salt of a dicarboxylic acid having 3 to 24 carbon atoms mixed with salts of said polyhydroxycarboxylic acids hydrolysis product.
 6. The process of claim 1, in which said salts to be used for the hydrolysis are the sodium salts.
 7. The process of claim 1, in which the concentration of the salt solutions is at least 2 percent.
 8. The process of claim 7, in which the concentration of the salt solution is from 20 percent to almost saturation at about 90*C.
 9. The process of claim 1, in which the salt solution used for the hydrolysis is recycled.
 10. The process of claim 1, in which said salts are the alkali metal salts.
 11. The process of claim 1, in which said epoxycarboxylic acids are epoxidized higher fatty acids having from 6 to 24 carbon atoms.
 12. The process of claim 11, in which said epoxidized higher fatty acid is epoxystearic acid. 